Expression and functional significance of the endocannabinoid system in human spermatozoa

Abstract

ObjectiveΔ9-Tetrahydrocannabinol disrupts endocannabinoid signalling through the cannabinoid receptor 1 (CB1) which accounts for the adverse reproductive consequences observed in marijuana users. How deregulation of the endogenous signalling pathway affects human sperm functions remains largely unexplored. The purpose of this study was to elucidate the pathophysiological role of the endocannabinoid system (ECS) in male fertility.DesignProspective laboratory based clinical study.Materials and MethodsSeminal plasma anandamide (AEA) was quantified by Ultra high performance liquid chromatography-tandem mass spectrometry from 90 semen samples provided by men with normal and abnormal semen parameters. Using qRT-PCR, CB1, CB2, NAPEPLD and FAAH mRNA expression profiles were characterized in human spermatozoa from men with normal and abnormal semen parameters. We evaluated in vitro, the effects of methanadamide (Met-AEA), a non-hydrolyzable analog of AEA, on sperm motility and mitochondrial membrane potential.ResultsAEA concentration was lower in asthenozoospermics (P=0.002), oligoasthenoteratozoospermics (P=0.001) and azoospermics (P=0.01) compared to normozoospermic controls. CB1 mRNA was decreased in asthenozoospermics (p < 0.0001) and oligoasthenoteratozoospermics (P < 0.0001). There were no significant differences in the expression of CB2, NAPEPLD or FAAH mRNA in abnormal human spermatozoa. Exposure of human spermatozoa to Met-AEA significantly decreased sperm motility through inhibition of mitochondrial membrane potential in a dose dependent manner. The inhibitory effect of Met-AEA was attenuated by the CB1 antagonist AM 251.ConclusionNormal regulation of the ECS may be necessary for the preservation of normal sperm function and male fertility. These observations highlight a potential toxicity mechanism for exocannabinoids (marijuana) and identifies the ECS as a potential target for treatment of male fertility. ObjectiveΔ9-Tetrahydrocannabinol disrupts endocannabinoid signalling through the cannabinoid receptor 1 (CB1) which accounts for the adverse reproductive consequences observed in marijuana users. How deregulation of the endogenous signalling pathway affects human sperm functions remains largely unexplored. The purpose of this study was to elucidate the pathophysiological role of the endocannabinoid system (ECS) in male fertility. Δ9-Tetrahydrocannabinol disrupts endocannabinoid signalling through the cannabinoid receptor 1 (CB1) which accounts for the adverse reproductive consequences observed in marijuana users. How deregulation of the endogenous signalling pathway affects human sperm functions remains largely unexplored. The purpose of this study was to elucidate the pathophysiological role of the endocannabinoid system (ECS) in male fertility. DesignProspective laboratory based clinical study. Prospective laboratory based clinical study. Materials and MethodsSeminal plasma anandamide (AEA) was quantified by Ultra high performance liquid chromatography-tandem mass spectrometry from 90 semen samples provided by men with normal and abnormal semen parameters. Using qRT-PCR, CB1, CB2, NAPEPLD and FAAH mRNA expression profiles were characterized in human spermatozoa from men with normal and abnormal semen parameters. We evaluated in vitro, the effects of methanadamide (Met-AEA), a non-hydrolyzable analog of AEA, on sperm motility and mitochondrial membrane potential. Seminal plasma anandamide (AEA) was quantified by Ultra high performance liquid chromatography-tandem mass spectrometry from 90 semen samples provided by men with normal and abnormal semen parameters. Using qRT-PCR, CB1, CB2, NAPEPLD and FAAH mRNA expression profiles were characterized in human spermatozoa from men with normal and abnormal semen parameters. We evaluated in vitro, the effects of methanadamide (Met-AEA), a non-hydrolyzable analog of AEA, on sperm motility and mitochondrial membrane potential. ResultsAEA concentration was lower in asthenozoospermics (P=0.002), oligoasthenoteratozoospermics (P=0.001) and azoospermics (P=0.01) compared to normozoospermic controls. CB1 mRNA was decreased in asthenozoospermics (p < 0.0001) and oligoasthenoteratozoospermics (P < 0.0001). There were no significant differences in the expression of CB2, NAPEPLD or FAAH mRNA in abnormal human spermatozoa. Exposure of human spermatozoa to Met-AEA significantly decreased sperm motility through inhibition of mitochondrial membrane potential in a dose dependent manner. The inhibitory effect of Met-AEA was attenuated by the CB1 antagonist AM 251. AEA concentration was lower in asthenozoospermics (P=0.002), oligoasthenoteratozoospermics (P=0.001) and azoospermics (P=0.01) compared to normozoospermic controls. CB1 mRNA was decreased in asthenozoospermics (p < 0.0001) and oligoasthenoteratozoospermics (P < 0.0001). There were no significant differences in the expression of CB2, NAPEPLD or FAAH mRNA in abnormal human spermatozoa. Exposure of human spermatozoa to Met-AEA significantly decreased sperm motility through inhibition of mitochondrial membrane potential in a dose dependent manner. The inhibitory effect of Met-AEA was attenuated by the CB1 antagonist AM 251. ConclusionNormal regulation of the ECS may be necessary for the preservation of normal sperm function and male fertility. These observations highlight a potential toxicity mechanism for exocannabinoids (marijuana) and identifies the ECS as a potential target for treatment of male fertility. Normal regulation of the ECS may be necessary for the preservation of normal sperm function and male fertility. These observations highlight a potential toxicity mechanism for exocannabinoids (marijuana) and identifies the ECS as a potential target for treatment of male fertility.